citric acid, esters with dodecan-1-ol

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-06-01 to 2016-08-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Didodecyl hydrogen citrate

EC Number:

247-146-3

EC Name:

Didodecyl hydrogen citrate

Cas Number:

25637-88-1

Molecular formula:

C30H56O7

IUPAC Name:

didodecyl hydrogen citrate

Constituent 2

Reference substance name:

Tridodecyl 2-hydroxypropane-1,2,3-tricarboxylate

EC Number:

265-671-6

EC Name:

Tridodecyl 2-hydroxypropane-1,2,3-tricarboxylate

Cas Number:

65277-53-4

Molecular formula:

C42H80O7

IUPAC Name:

tridodecyl citrate

Constituent 3

Reference substance name:

Dodecyl dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate

EC Number:

278-950-2

EC Name:

Dodecyl dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate

Cas Number:

78568-45-3

Molecular formula:

C18H32O7

IUPAC Name:

2-[2-(dodecyloxy)-2-oxoethyl]-2-hydroxysuccinic acid

Test material form:

solid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany; withdrawn on June 23th, 2016
- Storage conditions: kept aerobic until use
- Concentration of sludge: concentration used in the test was 29.6 mg dry mass/litre

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

100 mg/L

Based on:

act. ingr.

Initial test substance concentration 2

Initial conc.:

32 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: as stipulated in OECD guideline 301
- Additional substrate: no
- Test temperature: 22°C ± 1°C
- pH: 7.4 ± 0.2
- pH adjusted: no
- Aeration of dilution water: yes
- Suspended solids concentration: 29.6 mg/L
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: closed 500 mL glass vessels at a medium volume of 250 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration
- Measuring equipment: SAPROMAT respirometer (VOITH Inc.)
- Details of trap for CO2 and volatile organics if used: carbon dioxide is adsorbed in a suitable adsorbent
- Other: The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask.

SAMPLING
- Sampling frequency: measurement and recording of the oxygen demand was carried out continuously
- At test end, NH3-N and NO3-N concentrations were measured in control, test item and abiotic control assays.

CONTROL AND BLANK SYSTEM
Blank control: The blank control consists of inoculated mineral medium only.
Abiotic control: An abiotic control containing test item at 100 mg per litre sterilized mineral test medium (25 mg/250 mL) was applied. The assay was sterilized by adding HgCl2.
Procedural control: A procedural control containing sodium benzoate as reference item at 100 mg per litre mineral test medium (25 mg/250 mL) was applied.
Toxicity control: A toxicity control containing test item at 100 mg per litre and reference item at 100 mg per litre mineral test medium (25 mg/250 mL) was applied.


STATISTICAL METHODS:

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

100 mg/L

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

13.6

St. dev.:

2

Sampling time:

14 d

Remarks on result:

other: 100 mg/L

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

31.7

St. dev.:

2.3

Sampling time:

28 d

Remarks on result:

other: 100 mg/L

% Degradation 3

Parameter:

% degradation (O2 consumption)

Value:

25.5

St. dev.:

0

Sampling time:

14 d

Remarks on result:

other: 32 mg/L

% Degradation 4

Parameter:

% degradation (O2 consumption)

Value:

46.1

St. dev.:

0.9

Sampling time:

28 d

Remarks on result:

other: 32 mg/L

Details on results:

The biodegradation of the test item after 28 days of incubation in the static test was found to be 32 % (SD = 2.3 %) and 46 % (SD = 0.9 %) in the assays with 100 mg/L and 32 mg/L, respectively. The biodegradation within the 10-day-window was 18 % and 25 % in the assays with 100 mg/L and 32 mg/L, respectively. The 10-day-window started at day 3 for a concentration of 32 mg test item per liter and at day 8 - 11 for a concentration of 100 mg test item per liter.
The biodegradation of the item mixture in the toxicity control was found to be 39 % after 14 days of incubation. Thus, the demanded threshold value of 25 % is exceeded and the test item can be identified as non-toxic in a ready biodegradability test. The reference item sodium benzoate was degraded to 84 % within the first 14 days.
According to the OECD guideline 301F, the test item must be considered as being not readily biodegradable under the test conditions.

BOD5 / COD results

Results with reference substance:

The reference item sodium benzoate was degraded to 91 % within the first 14 days.

Any other information on results incl. tables

Oxygen consumption. Cumulated consumption (mg O₂/L) after 14 days: Single and mean values of the parallel test vessels and standard deviation. Test suspension A, abiotic and procedural control: 100 mg/L; Test suspension B: 24 mg/L;Toxicity control: 200 mg/L.

vessel	Inoculum blank	Test suspension A	Test suspension B	Procedural control	Toxicity control	Abiotic control
1	10	48	31	150	175	2
2	11	41	31	152	173	1
Mean	11	45	31	151	174	2
SD	1	5	0	1	1	1

 

Oxygen consumption. Cumulated consumption (mg O₂/L) after 28 days: Single and mean values of the parallel test vessels and standard deviation. Test suspension A, abiotic and procedural control: 100 mg/L; Test suspension B: 24 mg/L;Toxicity control: 200 mg/L.

vessel	Inoculum blank	Test suspension A	Test suspension B	Procedural control	Toxicity control	Abiotic control
1	15	101	54	163	232	6
2	20	93	55	164	233	3
Mean	18	97	55	164	233	5
SD	4	6	1	1	1	2

 

Percent degradation. Degradation after 14 days: Single and mean values of the parallel test vessels and standard deviation.

vessel	Test suspension A	Test suspension B	Procedural control	Toxicity control	Abiotic control
1	14.9	25.5	83.8	39.4	0.8
2	12.2	25.5	85.0	38.9	0.4
Mean	13.6	25.5	84.4	39.2	0.6
SD	2.0	0	0.8	0.3	0.3

 

Percent degradation. Degradation after 28 days: Single and mean values of the parallel test vessels and standard deviation.

vessel	Test suspension A	Test suspension B	Procedural control	Toxicity control	Abiotic control
1	33.3	45.5	87.4	51.4	2.4
2	30.1	46.7	88.0	51.6	1.2
Mean	31.7	46.1	87.7	51.5	1.8
SD	2.3	0.9	0.4	0.2	0.8

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In this test the test substance was not readily biodegradable.

Executive summary:

The biodegradation of the substance was investigated in a study conducted according to OECD Guideline 301 F, adopted 17th July 1992 (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D, 2008, over a period of 28 days using activated sludge sampled from a sewage treatment plant mainly fed with municipal wastewater as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank, toxicity control and procedural/functional control with the reference substance Sodium benzoate were performed. The test was performed with 32 and 100 mg/L test substance concentration.The functional control reached the pass level >60% after 14 d (84%).

The biodegradation of the test item after 28 days of incubation in the static test was found to be 32 % (SD = 2.3 %) in the assays with 100 mg/L and 46 % (SD = 0.9 %) in the assays with 32 mg/L.

For a concentration of 100 mg test item per liter biodegradation within the 10-day window was found to be 18 %. For a concentration of 32 mg test item per liter biodegradation within the 10-day-window was found to be 25 %. The 10-day-window started at day 3 for a concentration of 32 mg test item per liter and at day 8 - 11 for a concentration of 100 mg test item per liter.

The degradation of the reference substance sodium benzoate had reached 84 % within the first 14 days. The difference of extremes of replicate values of the removal of the test item at the end of the test for 100 mg/L and 32 mg/L, respectively, is less than 20%. Therefore, the test can be considered as valid. No inhibitory effects of the test item were observed (more

than 25 % degradation occurred within 14 days) in the toxicity control.

According to the guideline, PC-2016-670 must be considered as being not readily biodegradable under the test conditions.